Heretofore, physical examination of the human body for abnormalities, as for example, extradural and subdural hematomas, lesions and other masses, has been accomplished by the use of expensive and/or invasive diagnostic equipment. Three examples of such equipment, in addition to X-rays, are the computer tomography (CT) scanner, the magnetic resonance imaging (MRI) and the positron emission tomography device, each of which are employed to provide an image of a patient's tissue. Because of the cost and the technical complexity, the availability of such equipment is limited to major hospitals and clinics. Where X-ray equipment is used, it must be employed in a guarded environment to protect the operating technician and the patient from radio-active contamination and therefore is relatively costly. Another expensive diagnostic apparatus in common use employs ultra-high frequency sound; that is sound of a frequency above that audible by the human ear, which is in the range of 20,000 vibrations per second and above. This procedure has not proven entirely satisfactory for the detection of brain abnormalities because the short length of the ultra-high frequency wave is scattered by the bone structure of the head whereas diagnosis depends upon reception of the sound wave along the same axial path as the applied sound wave.
A non-invasive and inexpensive method of detecting the presence of an abnormality in the human body is known as auscultatory percussion. This method consists of applying a low frequency sound wave directly to the body such as the head or breast bone by finger tapping, a vibrator, or a sound generator. A stethoscope is applied successively from one side to the opposite side of the head or in the case of a chest examination to successive areas of the posterior chest wall to discern whether or not there is any diminished resonance or dullness. A change in the intensity of the sound is an indication of an abnormality since sound waves are attenuated by a medium of different density and/or physical character lying within an otherwise uniform material. Less sound energy is transmitted through the diseased area when compared to the opposite uninvolved area of the head or chest. The change in sound energy is measurable and enables detection and monitoring of the progress of disease in response to treatment. This concept was developed and applied by one of the co-inventors in his examination for diagnosing brain disease. By tapping with the pulp of his finger at a marked point in the midline of the upper forehead above the frontal sinuses, and applying the stethoscope alternately from one side to the opposite side of the head at corresponding anatomical areas, the inventor was able to determine and compare differences in sound between the opposite sides of the head.
The inventor also applied his method of auscultatory percussion in diagnosing chest disease by tapping lightly on the patient's breast bone with his finger, while listening with the stethoscope applied to the posterior chest wall. Percussion is applied with equal intensity over the same area of the breast bone, while the stethoscope explores both lung fields systematically to detect differences in sound transmission. In a controlled blind study of 28 patients with prominent chest disease determined by X-rays, each had normal or equivocal findings by conventional methods of percussion. In each of the 28 patients lung abnormality was readily detected by the author's method of auscultatory percussion.